I have recently met one older gentleman who does have dementia, along with other health difficulties, and who is able to explain that it affects his memory and his ability to complete a task. But he isn't making excuses for poor behaviour, he's working with us to manage his daily routine as well as possible and is aware of dementia as an obstacle to overcome.
A person in the later stages of dementia would neither see the need nor be able to construct the argument to excuse bad behaviour on account of it.
So: no. But having a vile temper of course does not stop you getting dementia *as well.*
I think that this would be fairly early on when they notice and are attempting to come to grips with their failing capabilities. I can remember when the husband of one of the former regulars on AgingCare had difficulties they would characterize it as a problem with "Lewy" (he had lewy body dementia).
That's what I would think, but she was diagnosed several years ago, and at this point has no idea of the time, day, time passing, dates, even the year. She has zero short term, although some things stick. Especially anything to do with drama. LOL She can't work the TV remote or her phone.. except to make an outgoing call by using "recents". And needs help sometimes picking out something to wear. So many task abilities, and comprehension about just about anything, have fallen away. She forgets who a favorite person is if I mention their name, but then can talk to them like she's totally fine when she does see them. But if she gets mad and pitches a fit, it's bad.. and then she'll apologize and say "sorry, it's just my dementia that makes me do that". I can actually see the issues being caused by dementia, but I wonder if, had she not been told it was dementia, she would still use that when she acted badly. Before she even got to this stage. I could write a book on what transpired over the past year. It's been quite a ride. Especially when family tells you.. " OH no... she's always acted like that.". Yikes. They just now have started to see the falling way of her filters and abilities. And she's really changed in the past few months.
I have the feeling, a lot of what I saw in the beginning of my stay here, was actually personality issues she had all her life. But when they told her about the dementia, it became a crutch. Now I see the dementia. And it's really coming quickly.
A person in the later stages of dementia would neither see the need nor be able to construct the argument to excuse bad behaviour on account of it.
So: no. But having a vile temper of course does not stop you getting dementia *as well.*